3. Edwards Aquifer
• Balcones Fault Zone
• Limestone and Artesian Aquifer
• Aquifer responds directly to pumping or recharge
• 4350 square miles
• Austin, San Marcos, New Braunfels, San Antonio
• Headwaters to San Marcos and Comal Springs
4. Edwards Aquifer cont.
• Guadalupe River baseflow
• Home to Endangered Species
• Comal Springs Dryopid Beetle
• Comal Springs Riffle Beetle
• Fountain Darter
• Peck’s Cave Amphipod
• San Marcos Salamander
• San Marcos Gambusia
• Texas Blind Salamander
• Texas Wild Rice
5. Demands on Edwards Aquifer
• Municipal Water
• Agriculture Use
• Industrial Use
• Recreational
• Biological
• Spring Flow
• Pumping vs. Springflow
Pumping vs Springflow
6. Limitations of the Edwards Aquifer
• 1956 Drought of Record– Comal Springs ceased to flow for 6 months
• Increased demand
• San Antonio: population of 2 million
• Surrounding communities
• Increased Development / Reduced Recharge
• Drought magnifies all
• Endangered Species Act of 1973
7. Legal Challenges
• Sierra Club v USFWS 1991
• Sierra Club alleged that unrestricted withdrawals from the aquifer would cause
take of Endangered Species. Courts agreed and established “take” and
“jeopardy” flow rates; water supply restrictions
• 2012 Deadline for “Continuous Minimum Springflows” for the species
• Senate Bill 1477 - 1993
• Established EAA and set withdrawal limits